1. Field of the Invention
This invention relates generally to electrical wiring installations and more particularly to a liquid tight connector for flexible non-metallic electrical conduit.
2. Antecedents of the Invention
Liquid tight connectors for joining electrical conduit to junction boxes were primarily relegated to compression fittings and the like employing a compressible ring which encircled the conduit, together with a compression nut which served to compress the ring, as exemplified in U.S. Pat. No. 3,659,880.
Connectors for metallic conduit have been known to employ self-tapping internal threads into which the end of the conduit was rotatably driven. A typical example of such connectors is illustrated in U.S. Pat. No. 2,580,818. Such connectors required the employment of tools such as pipe wrenches in order to attain sufficient torque to deform the conduit and were unsuited for liquid tight applications.
In connection with a non-metallic flexible conduit, there has been proposed the employment of a connector comprising a threaded sleeve which engaged the inner wall of the conduit. The outer surface of the conduit was overlaid by a separate ferrule.
Other types of liquid tight connectors required a compressible sealing gasket, especially when the end of the conduit length was not cut along a perfect transverse plane.